1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2006 Matthew Wilcox <matthew@wil.cx>
4 * Copyright (C) 2006-2009 Hewlett-Packard Development Company, L.P.
5 * Alex Chiang <achiang@hp.com>
6 */
7
8#include <linux/kobject.h>
9#include <linux/slab.h>
10#include <linux/module.h>
11#include <linux/pci.h>
12#include <linux/err.h>
13#include "pci.h"
14
15struct kset *pci_slots_kset;
16EXPORT_SYMBOL_GPL(pci_slots_kset);
17
18static ssize_t pci_slot_attr_show(struct kobject *kobj,
19 struct attribute *attr, char *buf)
20{
21 struct pci_slot *slot = to_pci_slot(kobj);
22 struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
23 return attribute->show ? attribute->show(slot, buf) : -EIO;
24}
25
26static ssize_t pci_slot_attr_store(struct kobject *kobj,
27 struct attribute *attr, const char *buf, size_t len)
28{
29 struct pci_slot *slot = to_pci_slot(kobj);
30 struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
31 return attribute->store ? attribute->store(slot, buf, len) : -EIO;
32}
33
34static const struct sysfs_ops pci_slot_sysfs_ops = {
35 .show = pci_slot_attr_show,
36 .store = pci_slot_attr_store,
37};
38
39static ssize_t address_read_file(struct pci_slot *slot, char *buf)
40{
41 if (slot->number == 0xff)
42 return sysfs_emit(buf, fmt: "%04x:%02x\n",
43 pci_domain_nr(bus: slot->bus),
44 slot->bus->number);
45
46 return sysfs_emit(buf, fmt: "%04x:%02x:%02x\n",
47 pci_domain_nr(bus: slot->bus),
48 slot->bus->number,
49 slot->number);
50}
51
52static ssize_t bus_speed_read(enum pci_bus_speed speed, char *buf)
53{
54 return sysfs_emit(buf, fmt: "%s\n", pci_speed_string(speed));
55}
56
57static ssize_t max_speed_read_file(struct pci_slot *slot, char *buf)
58{
59 return bus_speed_read(speed: slot->bus->max_bus_speed, buf);
60}
61
62static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)
63{
64 return bus_speed_read(speed: slot->bus->cur_bus_speed, buf);
65}
66
67static void pci_slot_release(struct kobject *kobj)
68{
69 struct pci_dev *dev;
70 struct pci_slot *slot = to_pci_slot(kobj);
71
72 dev_dbg(&slot->bus->dev, "dev %02x, released physical slot %s\n",
73 slot->number, pci_slot_name(slot));
74
75 down_read(sem: &pci_bus_sem);
76 list_for_each_entry(dev, &slot->bus->devices, bus_list)
77 if (PCI_SLOT(dev->devfn) == slot->number)
78 dev->slot = NULL;
79 up_read(sem: &pci_bus_sem);
80
81 list_del(entry: &slot->list);
82
83 kfree(objp: slot);
84}
85
86static struct pci_slot_attribute pci_slot_attr_address =
87 __ATTR(address, S_IRUGO, address_read_file, NULL);
88static struct pci_slot_attribute pci_slot_attr_max_speed =
89 __ATTR(max_bus_speed, S_IRUGO, max_speed_read_file, NULL);
90static struct pci_slot_attribute pci_slot_attr_cur_speed =
91 __ATTR(cur_bus_speed, S_IRUGO, cur_speed_read_file, NULL);
92
93static struct attribute *pci_slot_default_attrs[] = {
94 &pci_slot_attr_address.attr,
95 &pci_slot_attr_max_speed.attr,
96 &pci_slot_attr_cur_speed.attr,
97 NULL,
98};
99ATTRIBUTE_GROUPS(pci_slot_default);
100
101static const struct kobj_type pci_slot_ktype = {
102 .sysfs_ops = &pci_slot_sysfs_ops,
103 .release = &pci_slot_release,
104 .default_groups = pci_slot_default_groups,
105};
106
107static char *make_slot_name(const char *name)
108{
109 char *new_name;
110 int len, max, dup;
111
112 new_name = kstrdup(s: name, GFP_KERNEL);
113 if (!new_name)
114 return NULL;
115
116 /*
117 * Make sure we hit the realloc case the first time through the
118 * loop. 'len' will be strlen(name) + 3 at that point which is
119 * enough space for "name-X" and the trailing NUL.
120 */
121 len = strlen(name) + 2;
122 max = 1;
123 dup = 1;
124
125 for (;;) {
126 struct kobject *dup_slot;
127 dup_slot = kset_find_obj(pci_slots_kset, new_name);
128 if (!dup_slot)
129 break;
130 kobject_put(kobj: dup_slot);
131 if (dup == max) {
132 len++;
133 max *= 10;
134 kfree(objp: new_name);
135 new_name = kmalloc(size: len, GFP_KERNEL);
136 if (!new_name)
137 break;
138 }
139 sprintf(buf: new_name, fmt: "%s-%d", name, dup++);
140 }
141
142 return new_name;
143}
144
145static int rename_slot(struct pci_slot *slot, const char *name)
146{
147 int result = 0;
148 char *slot_name;
149
150 if (strcmp(pci_slot_name(slot), name) == 0)
151 return result;
152
153 slot_name = make_slot_name(name);
154 if (!slot_name)
155 return -ENOMEM;
156
157 result = kobject_rename(&slot->kobj, new_name: slot_name);
158 kfree(objp: slot_name);
159
160 return result;
161}
162
163void pci_dev_assign_slot(struct pci_dev *dev)
164{
165 struct pci_slot *slot;
166
167 mutex_lock(&pci_slot_mutex);
168 list_for_each_entry(slot, &dev->bus->slots, list)
169 if (PCI_SLOT(dev->devfn) == slot->number)
170 dev->slot = slot;
171 mutex_unlock(lock: &pci_slot_mutex);
172}
173
174static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
175{
176 struct pci_slot *slot;
177
178 /* We already hold pci_slot_mutex */
179 list_for_each_entry(slot, &parent->slots, list)
180 if (slot->number == slot_nr) {
181 kobject_get(kobj: &slot->kobj);
182 return slot;
183 }
184
185 return NULL;
186}
187
188/**
189 * pci_create_slot - create or increment refcount for physical PCI slot
190 * @parent: struct pci_bus of parent bridge
191 * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
192 * @name: user visible string presented in /sys/bus/pci/slots/<name>
193 * @hotplug: set if caller is hotplug driver, NULL otherwise
194 *
195 * PCI slots have first class attributes such as address, speed, width,
196 * and a &struct pci_slot is used to manage them. This interface will
197 * either return a new &struct pci_slot to the caller, or if the pci_slot
198 * already exists, its refcount will be incremented.
199 *
200 * Slots are uniquely identified by a @pci_bus, @slot_nr tuple.
201 *
202 * There are known platforms with broken firmware that assign the same
203 * name to multiple slots. Workaround these broken platforms by renaming
204 * the slots on behalf of the caller. If firmware assigns name N to
205 * multiple slots:
206 *
207 * The first slot is assigned N
208 * The second slot is assigned N-1
209 * The third slot is assigned N-2
210 * etc.
211 *
212 * Placeholder slots:
213 * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
214 * a slot. There is one notable exception - pSeries (rpaphp), where the
215 * @slot_nr cannot be determined until a device is actually inserted into
216 * the slot. In this scenario, the caller may pass -1 for @slot_nr.
217 *
218 * The following semantics are imposed when the caller passes @slot_nr ==
219 * -1. First, we no longer check for an existing %struct pci_slot, as there
220 * may be many slots with @slot_nr of -1. The other change in semantics is
221 * user-visible, which is the 'address' parameter presented in sysfs will
222 * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
223 * %struct pci_bus and bb is the bus number. In other words, the devfn of
224 * the 'placeholder' slot will not be displayed.
225 */
226struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
227 const char *name,
228 struct hotplug_slot *hotplug)
229{
230 struct pci_dev *dev;
231 struct pci_slot *slot;
232 int err = 0;
233 char *slot_name = NULL;
234
235 mutex_lock(&pci_slot_mutex);
236
237 if (slot_nr == -1)
238 goto placeholder;
239
240 /*
241 * Hotplug drivers are allowed to rename an existing slot,
242 * but only if not already claimed.
243 */
244 slot = get_slot(parent, slot_nr);
245 if (slot) {
246 if (hotplug) {
247 if ((err = slot->hotplug ? -EBUSY : 0)
248 || (err = rename_slot(slot, name))) {
249 kobject_put(kobj: &slot->kobj);
250 slot = NULL;
251 goto err;
252 }
253 }
254 goto out;
255 }
256
257placeholder:
258 slot = kzalloc(size: sizeof(*slot), GFP_KERNEL);
259 if (!slot) {
260 err = -ENOMEM;
261 goto err;
262 }
263
264 slot->bus = parent;
265 slot->number = slot_nr;
266
267 slot->kobj.kset = pci_slots_kset;
268
269 slot_name = make_slot_name(name);
270 if (!slot_name) {
271 err = -ENOMEM;
272 kfree(objp: slot);
273 goto err;
274 }
275
276 INIT_LIST_HEAD(list: &slot->list);
277 list_add(new: &slot->list, head: &parent->slots);
278
279 err = kobject_init_and_add(kobj: &slot->kobj, ktype: &pci_slot_ktype, NULL,
280 fmt: "%s", slot_name);
281 if (err) {
282 kobject_put(kobj: &slot->kobj);
283 goto err;
284 }
285
286 down_read(sem: &pci_bus_sem);
287 list_for_each_entry(dev, &parent->devices, bus_list)
288 if (PCI_SLOT(dev->devfn) == slot_nr)
289 dev->slot = slot;
290 up_read(sem: &pci_bus_sem);
291
292 dev_dbg(&parent->dev, "dev %02x, created physical slot %s\n",
293 slot_nr, pci_slot_name(slot));
294
295out:
296 kfree(objp: slot_name);
297 mutex_unlock(lock: &pci_slot_mutex);
298 return slot;
299err:
300 slot = ERR_PTR(error: err);
301 goto out;
302}
303EXPORT_SYMBOL_GPL(pci_create_slot);
304
305/**
306 * pci_destroy_slot - decrement refcount for physical PCI slot
307 * @slot: struct pci_slot to decrement
308 *
309 * %struct pci_slot is refcounted, so destroying them is really easy; we
310 * just call kobject_put on its kobj and let our release methods do the
311 * rest.
312 */
313void pci_destroy_slot(struct pci_slot *slot)
314{
315 dev_dbg(&slot->bus->dev, "dev %02x, dec refcount to %d\n",
316 slot->number, kref_read(&slot->kobj.kref) - 1);
317
318 mutex_lock(&pci_slot_mutex);
319 kobject_put(kobj: &slot->kobj);
320 mutex_unlock(lock: &pci_slot_mutex);
321}
322EXPORT_SYMBOL_GPL(pci_destroy_slot);
323
324#if defined(CONFIG_HOTPLUG_PCI) || defined(CONFIG_HOTPLUG_PCI_MODULE)
325#include <linux/pci_hotplug.h>
326/**
327 * pci_hp_create_module_link - create symbolic link to hotplug driver module
328 * @pci_slot: struct pci_slot
329 *
330 * Helper function for pci_hotplug_core.c to create symbolic link to
331 * the hotplug driver module.
332 */
333void pci_hp_create_module_link(struct pci_slot *pci_slot)
334{
335 struct hotplug_slot *slot = pci_slot->hotplug;
336 struct kobject *kobj = NULL;
337 int ret;
338
339 if (!slot || !slot->ops)
340 return;
341 kobj = kset_find_obj(module_kset, slot->mod_name);
342 if (!kobj)
343 return;
344 ret = sysfs_create_link(kobj: &pci_slot->kobj, target: kobj, name: "module");
345 if (ret)
346 dev_err(&pci_slot->bus->dev, "Error creating sysfs link (%d)\n",
347 ret);
348 kobject_put(kobj);
349}
350EXPORT_SYMBOL_GPL(pci_hp_create_module_link);
351
352/**
353 * pci_hp_remove_module_link - remove symbolic link to the hotplug driver
354 * module.
355 * @pci_slot: struct pci_slot
356 *
357 * Helper function for pci_hotplug_core.c to remove symbolic link to
358 * the hotplug driver module.
359 */
360void pci_hp_remove_module_link(struct pci_slot *pci_slot)
361{
362 sysfs_remove_link(kobj: &pci_slot->kobj, name: "module");
363}
364EXPORT_SYMBOL_GPL(pci_hp_remove_module_link);
365#endif
366
367static int pci_slot_init(void)
368{
369 struct kset *pci_bus_kset;
370
371 pci_bus_kset = bus_get_kset(bus: &pci_bus_type);
372 pci_slots_kset = kset_create_and_add(name: "slots", NULL,
373 parent_kobj: &pci_bus_kset->kobj);
374 if (!pci_slots_kset) {
375 pr_err("PCI: Slot initialization failure\n");
376 return -ENOMEM;
377 }
378 return 0;
379}
380
381subsys_initcall(pci_slot_init);
382

source code of linux/drivers/pci/slot.c